import java.util.Scanner;

/**
 * @author : niu niu
 * @version : 1.0.0
 * @date : 2023/3/30 23:52
 */
public class TestTest {
    public static void main(String[] args) {
        Scanner s = new Scanner(System.in);
        double x= s.nextDouble();
        double[] arr = new double[10];
        for (int i = 0; i < 10; i++) {
            arr[i] = s.nextDouble();
        }
        double sum = 0;
        for (int i = 0; i < 10; i++) {
            sum += Math.pow(arr[i] - x,2);
        }
        sum = sum/10;
        double res = Math.pow(sum,1.0/2);
        System.out.println(res);
    }
}
